Plasma cell tumors are lymphoid neoplastic proliferations of B cells that may be classified as multiple myeloma (MM), solitary bone plasmacytoma (SBP) and extramedullary plasmacytoma (PEM). These types of neoplasia are typically found in adults and may occur as disseminated tumors of the bone marrow or in some cases as solitary bone or extramedullary tumors. Most SBP eventually develop into MM, whereas only 30% of the PEM do so. Oral manifestations in the form of oral and maxillofacial lesions are often the first sign of the disease. Treatment of these neoplastic tumors varies depending on the type of proliferation and may involve surgery, radiotherapy and chemotherapy, alone or combined. This paper reviews the main clinical and pathological aspects of these tumors and their relationship to the oral and maxillofacial area.